Tom K. Whidden

Preparation and crystal structure of S2I42+(AsF6–)2 containing the distorted right triangular prismatic disulphur tetraiodine(2+) cation and a disulphur unit of bond order greater than two

S2I42+(AsF6–)2 has been prepared and its crystal structure determined in which the S2I42+ cation was found to have a distorted right triangular prismatic structure, with one S2 and two I2 units joined by weak sulphur–iodine bonds; the sulphur–sulphur bond distance is the shortest reported in an isolated compound, and is indicative of the presence of a 3pπ–3pπ bond and a bond order greater than two.

Application of a mid-infrared fiber bundle in remote measurement of gas concentrations in a chemical vapor deposition chamber

A fiber bundle has been designed for measurement of gas concentrations in a chemical vapor deposition (CVD) chamber. The bundle is broadband, covering the spectrum range from 500 to 6000 cm(-1). Using this bundle, we have designed Fourier Transform infrared (FTIR) sampling configurations with reduced beam divergence (from 0.4 to 0.1 rad) and focal spot diameters (from 12 to 4 mm). The FTIR spectrum of tetraethoxysilane vapors in a CVD chamber was determined with the bundle and modified SAM connectors. An ellipsoid reflector was designed that yielded improved signal-to-noise ratios (SNRs) in the fiber-based spectra by a factor of 2. The incorporation of this reflector in spectrometers by use of the fiber bundle has the potential to reduce the sampling times for spectra while retaining acceptable SNRs.

Synthesis of [N(CH3)4]2O3SOSO2(s) and [N(CH3)4]2[(O2SO)2SO2]·SO2(s) Containing (SO4)(SO2)x2–x = 1, 2, Members of a New Class of Sulfur Oxydianions

One mole equivalent of SO2 reversibly reacts with [N(CH3)4]2SO4(s) to give [N(CH3)4]2S2O6(s) (1) containing the [O3SOSO2](2-), shown by Raman and IR to be an isomer of the [O3SSO3](2-) dianion. The experimental and calculated (B3PW91/6-311+G(3df)) vibrational spectra are in excellent agreement, and the IR spectrum is similar to that of the isoelectronic O3ClOClO2. Crystals of [N(CH3)4]2(O2SO)2SO2·SO2 (2) were isolated from solutions of [N(CH3)4]2SO4 in liquid SO2. The X-ray structure showed that 2 contained the [(O2SO)2SO2](2-) dianion. The characterized N(CH3)4(+) salts 1 and 2 are the first two members of the (SO4)(SO2)x(2-) class of sulfur oxydianions analogous to the well-known small cation salts of the SO4(SO3)x(2-) polysulfates.

Preparation and X-ray crystal structure of iodocycloheptasulphur hexafluorantimonate(VI), [S7I]+[SbF6]–

The salts [SxI]+[MF6]–(x= 7 or possibly 8, M = As or Sb) have been prepared by various reactions; the crystal structure of [S7I]+[SbF6]– shows the cation to contain iodine bonded to a sulphur atom of a seven-membered sulphur ring.

Preparation and characterisation of adducts of bismuth pentafluoride and antimony pentafluoride by vibrational spectroscopy, X-ray powder diffraction, and single-crystal X-ray crystallography

Adducts between BiF5 and SbF5 were prepared in liquid WF6 at room temperature. Sublimation of the product gave various volatile crystalline products with analyses corresponding to BiF5(SbF5)3, BiF5(SbF5)2, BiF5(SbF5)1.5, and (BiF5)nSbF5(n= 2, 3, or 20.6). The adducts (BiF5)nSbF5(n= 1 or 1.5), were also prepared. The BiF5(SbF5)n(n= 1.5, 2, or 3) adducts were of low melting point and of higher volatility than (BiF5)nSbF5(n 1). Single-crystal X-ray diffraction studies showed that BiF5(SbF5)n(n= 2 or 3) were isomorphous with tetrameric (NbF5)4, and an X-ray powder diffraction photograph of BiF5(SbF5)1. was very similar to that of BiF5(SbF5)n(n= 2 or 3), indicating that it was also isostructural with (NbF5)4. The BiF5(SbF5)3 structure likely consists of disordered BiF5(SbF5)3 tetramers, and BiF5(SbF5)2 likely consists of a mixture of disordered BiF5(SbF5)3 and (BiF5.SbF5)2 tetramers in the appropriate ratios. The molecular-beam mass spectra of SbF5(BiF5)n(n= 2 or 3) show fragment ions attributable to BiF5 and SbF5 as well as various associated pentafluoride clusters, including BiF5(SbF5)3 for the n= 3 adduct. The vibrational spectra of BiF5(SbF5)n(n= 1.5, 2, or 3) were similar and indicative of the presence of SbF5 and BiF5 units joined by cis-bridged fluorine atoms. (BiF5)nSbF5(n= 1, 1.5, 2, 3, or 20.6), were shown by X-ray powder diffraction photography to be isomorphous with polymeric trans-bridged BiF5 and therefore to consist of disordered BiF5 and SnF5 units linked by trans-bridged fluorine atoms. The trans-bridged polymeric BiF5-type structure of the adducts was further supported by their vibrational spectra. The behaviour of BiF5-(SbF5)n(n= 2 or 3) in WF6 solution is discussed. An estimated phase diagram for the system BiF5–SbF5 was constructed.

Adducts of bismuth pentafluoride with antimony pentafluoride

Abstract Bismuth pentafluoride reacts with SbF5 to form adducts of the type (BiF5)m (SbF5)n, m:n ⩾1 which have a trans -fluorine bridged BiF5 type structure, and BiF5.1.53SbF5, BiF5.2SbF5, and BiF5.3SbF5 which are isomorphous with NbF5 and are, therefore, cis -fluorine bridged tetramers. The BiF5.2SbF5 adduct probably consists of disordered (BiF5.3SbF5) and (2BiF5.2SbF5) tetramers in a 2:1 ratio, BiF5.3SbF5 has a tetrameric structure, and the BiF5.1.53SbF5 adduct probably consists of discrete (BiF5.3SbF5) and (2BiF5.2SbF5) tetramers in the appropriate ratio.